7/25/2012

Hypothermia And Cold Injuries


(Adapted from "Princeton University Outdoor Action Guide to Hypothermia and Cold Weather Injuries" by Rick Curtis)
  • Introduction
  • Prevention of Hypothermia
  • Signs of Hypothemia
  • Treatment of Hypothermia
  • Frost Bite
  • Trench Foot

Introduction


We expect that hypothermia will be a major concern if the weather is cold and the protesters are not adequately prepared to be exposed to cold for a long time. Quebec is a chilly and windy province. Remember, most people are outside in the winter for less than 30 minutes at a time. Few are out for more than two hours. With global climate change, the weather can change unpredictably for the season.  

Hypothermia occurs when the body cools down too much because of cold weather or being wet and cool.
Risk Factors: Cool, cold, wet, or windy environment. Improper clothing and equipment. Fatigue. Dehydration. Age. Immobility. Poor food intake. No Knowledge of Hypothermia. Alcohol intake, cigarettes. Poor circulation. Not taking hypothermia seriously.

Prevention of hypothermia and cold injuries:


· Keep well hydrated, drink at least 2-3 liters a day. Warm blood circulation is key.
· Eat energy foods such as carbohydrates.
· Dress appropriately for long term exposure to the weather. This cannot be stressed enough. Have the attitude that you are going camping, and need to remain comfortable during the various weather - and without the luxury of being able to get to shelter as needed. In the morning, it will be chilly or cold - you will need warm clothes layers. The afternoon will be warmer, and to keep from sweating, you will need to remove layers. In the evening/night, it will get cold again. It could rain so you need to stay dry. Insulate with layers of dry clothes that can breath (let body moisture escape). Think about : winter gear, long underwear, water resistant outer clothes, snowsuits, warm boots, hat & gloves, etc.
· Carry extra dry clothes. Especially socks and shirts.
· Make sure clothes, boots and gloves are not constricting with the layers. Tight clothes, boots and gloves may constrict circulation of warm blood, and can decrease the insulation ability of the materials.
· Avoid local pressure, cramped position.
· If you are going to be immobile, or on the ground: You need extra insulation - both clothes and ground protection. Think about padded hockey pants, foam padding, etc.
· Gear: consider hand and feet warmers, aluminum space blankets, thermos.
· Prevent getting wet - water resistant outer gear is not only good against rain & water, but also works fine against wind, tear gas and pepper spray.
· Wear shell on the outside against wind - if no risk of getting wet or exposed to chemicals.
· Clothes next to skin must be of materials such as synthetics or wool, that can wick away sweat. Cotton (our most common clothing material) next to skin is bad - it soaks up sweat and you remain wet.
· If you know that overheating is not a risk factor, consider antiperspirant to reduce sweating. (Especially on feet)
· A warm hat is a must - we loose a significant amount of heat through our head.
· Avoid cigarettes and diuretics such as coffee or alcohol as they shunt warm blood away from skin.
· "Buddy system" keep a regular watch on each other's faces, ask about hands & feet sensation.
· Regular "self check" for cold areas, wet feet, numbness.
· If at any time you discover a cold injury, stop & rewarm the area (unless doing so places you at greater risk).

Signs of Hypothermia:


Mild:
Shivering. Can't do complex motor functions with hands but can still walk and talk. Skin is cool due to vasoconstriction. Hands numb. If shivering can be stopped voluntarily, it is mild hypothermia. If a person cannot count backwards from 100, they could be hypothermic.

Moderate Hypothermia:

Shivering not under voluntary control . Loss of fine motor control - particularly in hands - can't zip up coat - due to restricted peripheral blood flow. Uncoordination.
May have: Dazed consciousness. Slurred speech. Violent shivering. Irrational behaviour - may even undress unaware that s/he is cold. "I don't care attitude" - flat emotions/affect.

Severe Hypothermia: 
(Don't let it get this far!): Shivering occurs in waves until shivering finally ceases. Irrational. May be able to maintain posture and appearance of awareness. Progresses to: Person can't walk, curls up into fetal position to conserve heat. Muscle rigidity. Skin is pale. Pupils dilate (become big). Pulse rate decreases. As it progresses, breathing and heart rate decreases. Then the person looks dead, but is still alive.

 

Treatment of Hypothermia:


Hypothermia can develop into a medical emergency. The person must be re-warmed.

Mild to Moderate Hypothermia
The best way is by the person's own body heat. Replace wet clothes with dry clothes. Additional layers of dry clothes & blankets to insulate the person against escaping body heat. Increase physical activity. Consider: Get out of cold. Add Fuel & Fluids: Carbohydrates are quick (best in mild hypothermia) and Proteins which gives a slower heat over a longer time. Fats give off heat slower and longer, but takes more energy & water to break down fat.

Inefficient ways: Hot drinks. Feels better than is effective. Careful not to burn mouth/tongue.

Add Heat: External heat source (warm room).
If outside: body to body contact - get into a sleeping bag in dry clothing with a warm person in lightweight dry clothing. Heat pads.

Severe Hypothermia
1. Reduce Heat Loss:
Hypothermia wrap: Provide a shell of total insulation. No matter how cold, the patient can still internally rewarm themselves more efficiently than any external rewarming. Make sure patient is dry, with synthetic layer to minimize sweating on skin. Use multiple layers, foam, etc. to create insulation. Include aluminum "space" blanket to prevent radiant heat loss.

2. Add Fuel & Fluids:
Warm Sugar Water - With severe hypothermia, stomach shuts down and wont absorb solid foods. Dilute mixture of warm water w sugar every 15 minutes. Dilute Jello works best since it is part sugar part protein.
Urination: A full bladder is a place for extra heat loss. You will need to help the person urinate.

3. Add Heat:
Hot water bottles, hot pads, etc. to transfer heat to major core arteries - neck, armpits, groin, palms of hands. Best to rewarm the core body this way only - not the arms & legs. (When person becomes hypothermic, blood is shunted away from arms/legs. If peripheral vessels open up, cold acidic blood from periphery goes to core - may cause heart arrhythmias and death.
 
Frostbite
· Happens only in temperature below freezing. If tissue freezes, ice crystals form in cells. Distal areas of body most susceptible: ears, nose, fingers & toes.
· Treatment: Do not rub tissue: can damage cells from ice crystals. Rewarm gently. If deep frostbite, consider immersion in warm (not hot) water 25 - 40 minutes. If hot - can burn damaged skin. Thawing is complete when part is pliable and colour and sensation return. Once area has rewarmed, there can be considerable pain.
· Wrap affected area in sterile gauze and protect from movement and further cold. Treat as a tissue injury - consider hospital if significant tissue damage.
· Once a body part has been rewarmed, it cannot be used for anything until tissue begins to repair. It is essential that in not be refrozen - causes more damage. If you cannot guarantee that the tissue will stay warm, do not rewarm it.
· If person is hypothermic and frostbitten: priority is treating hypothermia. Do not rewarm frostbitten areas until core is warm.


Trench Foot
Wet feet loose heat 25x faster than dry. The body uses vasoconstriction to shut down peripheral circulation in foot to prevent heat loss. Skin tissue than can begin to die. Can also cause permanent damage to the circulatory system making person more prone to cold related injuries. 


Prevention and Treatment of Trench foot:
· Keep feet dry. Water-proof boots. Check feet regularly (if wet from sweating or immersion), stop and dry feet, put on dry socks, consider plastic bag over dry socks / between wet boots - but beware of vapor barrier increasing sweat wetting foot.
· Some mountaineers will put antiperspirant with aluminum hydroxide on feet for a week before trip.
· Experiment to see if your feet sweat much. If not, consider vapor barrier. If so, use socks that wick away sweat, and water-proof boots. · If trench foot sets in, foot is more susceptible to damage by walking on it.

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